Means for controlling mercury-vapor electric lamps.



No. 809,643. PATENTED JAN. 9, 1906.

P. H. THOMAS. MEANS FOR CONTROLLING MERCURY VAPOR ELECTRIC LAMPS.

APPLICATION FILED APR. 23. 1904.

UNITED STATES PATENT OFFICE- PERCY H. THOMAS, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO COOPER HEWITT ELECTRIC COMPANY, OF NEWYYORK, N. Y., A

CORPORATION OF NEW YORK.

MEANS FOR CONTROLLING MERCURY-VAPOR ELECTRIC LAMPS- Specification of Letters Patent.

Patented Jan. 9, 1906.

Application filed April 23, 1904- Scrial N0. 204 ,6 17.

To all whom, it may concern.-

Be it known that I, PERCY H. THOMAS, a citizen of the United States, and a resident of East Orange, county of Essex, State of New Jersey, have invented certain new and useful Improvements in Means for Controlling Mercury-Vapor Electric Lamps, of which the following is a specification.

In starting mercury-vapor lamps by means of first establishing a bridge 'of mercury from the positive to the negative electrode an excessive current sometimes passes at the moment of establishing the bridge, this result being due to the fact that the vapor resistance is short-circuited by the film or stream of mercury. The same result may follow in cases where a bridge of mercury normally exists between the electrodes, which bridge is afterward broken in order to start the lamp into operation. Moreover, in cases where a supplemental positive electrode is used between which and the negative electrode a brid e of mercury is ruptured for locally brea ring down the negative-electrode resistance the same thing may happen. The excessive current referred to may cause a momentary ohmic drop in the lamp, which tends to put out other lamps in the circuit or to blow fuses.

The object of the present invention is to prevent this excessive current at the time of starting a vapor electric lamp by introducing in series with the electrodes a resistance having a negative temperature coefiieientsuch, for example, as a carbon filament. The resistance of such a filament is considerably higher when cold than when hot, and this difference may be made as great as two or three times.

In the series resistance which is contemplated herein a carbon filament having a suitable difference of resistance as between the hot and a cold state will be employed, such difference being suited to the conditions existing in connection with the particular lamp in question to be protected. During the moment when the current applied to the lamp is passing through the described short circuit the filament is cold, its resistance is relatively high, and after a suitable lapse of time subsequent to the introduction of the vapor resistance into the circuit by the breaking of the film or stream of mercury the filament becomes of less and less resistance until the predetermined normal value is reached. The filament may even be used as the normal steadying resistance for the lamp, or it may be replaced, automatically or otherwise, by such a resistance. This arrangement may advantageously be used in connection with a steadying resistance, such as an iron ballast, in series with the lamp.

In speaking of a vapor electric lamp I do not wish to exclude vapor apparatus employed for any purpose whatsoever.

For convenience I have illustrated the invention in connection with a mercury-vapor lamp of the tilting type, wherein the flow of current is initiated by establishing a stream of mercury between the positive and negative electrodes. I have also illustrated an iron ballast in series with the carbon filament and the vapor-lamp.

The drawing shows an elevation of a vapor-lamp having my invention applied to it.

In the drawing, 1 is the container of a vapor-lamp, having a positive electrode of mercury at 2 and a negative electrode, also of mercury, at 3. This lamp may be surrounded by a ring 4 and the, latter connected by a cord 5 with an operatingfring or handle 6 for the tilting of the lamp, so as to establish a stream of mercury in the first instance from I one electrode to the other, which stream is afterward broken on the release of the ring or handle 6 by the return of the lamp through gravity or other means to the position illustrated. The cord 5 may conveniently be arranged to pass through a pulley 7 for easy manipulation. The connection of the electrodes 2 and 3 with the external circuit is made by lead-wires 8 and 9, respectively. Both these lead-wires may be connected by loops (shown at 10 10) with the external circuit, so as to permit the manipulation of the lamp without injurious strain upon the external circuit-wires. The latter are shown at 11 and 12. In the circuit of the wire 11 I include a carbon filament 13, which may conveniently be the filament of an ordinary incandescent lamp. In series with the filament I may also include an iron ballast, (shown at 14,) the same consisting of an iron Wire 15 within an atmosphere of hydrogen in a container 16.

ICO

Owing to the relatively high resistance of the carbon filament 13, an excessive flow of current through the bridge of mercury when the lamp is first tilted is prevented. On the other hand, after the bridge has been broken and the lamp has been in operation for a sufficient period, usually a second or two, the filament becomes heated sufficiently to take the current necessary to supply the needs of the service.

The ballast resistance 14 and the filament 13 being duly proportioned will constitute a steadying resistance for the lamp, which will tend to maintain conditions of good operation at all times.

I claim as my invention The combination with a vapor electric apparatus which is adapted to be started byrupturing a conducting film or bridge between the electrodes, of a carbon filament in series with apparatus and a ballast also in series with the apparatus, said ballast having apositive temperature coefficient.

Signed at New York, in the county of New York and State of New York, this 6th day of April, A. D. 1904.

PERCY H. THOMAS.

Witnesses:

WM. H. OAPEL, GEORGE H. STooKBRIDeE. 

